It is known in the art that certain microorganisms, particularly certain microorganism mutants, form hexahydroindanone derivatives as intermediate degradation products in the degradation of steroid compounds. For example, it is known that a mutant strain derived from Nocardia corallina IFO 3338 will degrade cholesterol to form 3 a.alpha.-H-4.alpha.- (3'-propionic acid)-5.alpha.-hydroxy-7a.beta.-methyl-hexahydro-1-indanone-.delta.-lacton e, which has the following structural formula: ##STR1## See, e.g. T. Nakamatsu et al., Agric. Biol. Chem., 44(7), 1469-1474 (1980). The primary reaction product formed during the fermentation stage is the free carboxylic acid, 3-(5.alpha.-hydroxy-7a.beta.-methyl-1-oxo-3a.alpha.-H-hexahydroindane-4.al pha.-yl) propionic acid. When the fermentation broth containing this carboxylic acid is acidified with sulfuric acid to a pH of 2.0 or less, the .delta.-lactone of Formula I above is formed therefrom. See, e.g., French Pat. No. 2,387,288. Other authors report the conversion of sitosterol with the mutant Nocardia sp.M29 to the above hydroxy carboxylic acid. See V. Schomer et al., European J. Appl. Microbiol. Biotechnol.10, 99-106 (1980). Other disclosures regarding the formation of partial decomposition products of sterols, in particular sitosterol, can be found in the U.S. Pat. Nos. 4,176,123 and 4,042,459, as well as in the Federal Republic of Germany Pat. DE-OS 2,746,323. Even during microbial degradation of bile acids, the formation of hexahydro-1-indanone-.delta.- lactone could be detected--see Nakamatsu et al, supra, p. 1473, and Hashimoto et al, Biochem. J., 164,715 (1977).